1. Field of the Invention
This invention relates to an operating microscope used in, for example, surgical operations.
2. Description of the Related Art
An operating microscope is disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 7-16239. This operating microscope has an arm frame of a counterweight (counterbalance) type in which a lens barrel portion supported on an arm is supported for three-dimensional movement and a counterweight is used for total balancing.
Disclosed in Jpn. Pat. Appln. KOKAI Publication No. 57-86806 is an operating microscope having an arm frame of a spring-balance type in which a spring is used for total balancing. This arm frame can enable the overall weight or mass of the operating microscope to be less than the counterbalance-type arm frame, that is, it can make the operating microscope more compact. Thus, this operating microscope has an advantage of improved transportability.
The operating microscope having the spring-balanced arm frame thus disclosed in Jpn. Pat. Appln. KOKAI Publication No. 57-86806 includes a horizontal motion arm, which makes a lens barrel portion horizontally move around two vertical axes, and a vertical motion arm, which makes the lens barrel portion vertically move around one horizontal axis. This arm frame has a structure such that an angular moment generated around the one horizontal axis by the weight of the lens barrel portion or the weight of the vertical motion arm is canceled for balancing by an elastic member (coil spring, gas spring, etc.).
An operating microscope is disclosed in European Pat. Appln. Publication No. 1251380. This operating microscope is furnished with a leveling function having a solid structure such that a rotary swing bearing is attached to the arm frame and two vertical axes can be adjusted for leveling in the vertical direction without regard to inclination of a floor surface.